Fading regulation in television receivers



April 23, 1940. K. SCHLESINGER FADING REGULATION IN TELEVISION RECEIVERS2 Sheets-Sheet 1 Filed July 8, 1938 I Jm'enfop: v

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April 23, 1940.

K. 'SCHLESINGER FADING REGULATION IN TELEVISION RECEIVERS Filed July 8,1938 2 Sheets-Sheet 2 III J17 venioz== Patented Apr. 23, 1940Zflggfiflfl STATES PATENT @Fi' ifih'.

FADING REGULATION IN TELEVISION RECEIVERS Kurt Schlesinger, Berlin,Germany, assignor, by

mesne assignments, to Loewe Radio, Inc, a corporation of New YorkApplication July 8, 1938, Serial No. 218,164 In Germany August 30, 19374 Claims. (01. 1787.5)

For regulating the sensitivity of reception in nected with thedeflecting element of the Braun the case of television receivers methodsare em tube. plcyed which differ considerably from those According tothe invention, there is included usual in the radio art. For example, ithas been in the anode circuit of the end tube i the priproposed by theapplicant (application Ser No. mary coil of a transformer ii in parallelor in .3

53,534) to obtain the regulatin potential necesseries to the anoderesistance. To the secondsary for the fading compensation from thesynary coil there is connected the generator for obchronisation signals.This method, as comtaining the regulating potential. This transparedwith other methods in which the reguformer is prefera y tuned to thefrequency of lating potential is obtained from the carrier frethe imagechange signals. The potential tapped quency, possesses the advantagethat the sensiin the secondary Coil Ch y W y Of a 6 8 tivity ofreception is dependent solely on the 2 a condenser 3, with which thereis connected field intensity at the place of reception and is inparallel a resistance l. The time constant of proportional to this fieldintensity, as the synthe elements 3 and isas large as. any imagechronisation signals are always of constant size point- T e transformerShould be poled that 75 during the entire transmission and accordinglythe negative impulses arrive at the cathode of also vary in the sameproportion as the field the valve 2. The regulating potential is tappedintensity at the place of reception. The sensiat the terminals of theresistance i and is contivity of the reception is completely independentd c e o e a p e amplifying t b l0 of th t t of t image it m tubes of theintermediate-frequency amplifier.

It has been found that, in order to obtain a Th transformer 5 n be r p dy h h r proper regulation of the sensitivity of recepquency conde suplin tion, and accordingly a proper image, it is neces- T0 the grid 50f the triode 3 there is pp sary to make the sensitivity of receptionden he ne hand a pr f ably j able blockpendent solely on thesynchronisation signals potential 8 and on the other hand the relaxaforthe image change. tion potential for the image change. This ar- Theobject of the present invention i a oltrangement is such and is sodimensioned that age generating device for automatically fading heblockin f h rid 5 i in r p ed nly at compensating in a televisionreceiver comprising the image relaxa moment! e d 5 is m an amplifier foramplifying the re eiv d signals connected with the lead traversed by theimage and a relaxation oscillator for generating the relaxationDOT/911171911 p y y W y Of 2 011 frame deflecting voltage. According tothe ind s vention said voltage generating device is con- By means of theblocking potential 8 there nected on the one hand to the output of saidcan be adjusted the duration of the release of 1:3 amplifier, and on theother hand to the output the tube 2 from the blocking effect and alsothe of said frame relaxation oscillator so that it is extent of theregulating potential.

controlled by said amplifier and said oscillator in The arrangementaccording to the invention such a manner that the voltage generated bycan naturally also be employed in other fashion. said device isdependent only on the amplitude of For example, it is possible to giveinductively ii) the frame synchronizing signals given from the therelaxation oscillation at the grid 5 of the tube transmitter. 2. In thiscase a transformer is used, which is Fig. l. discloses one embodiment ofmy inven- Combined Dmferamy'v'vith a p h-p ll transformer t forObtaining automatic vomme Control to give the oscillation of relaxationgenerator at from the frame synchronizing sigmng the deflectingelements. This transformer is -13 Fig 2 discloses anothm. embodiment ofFig tuned to the period of return to give the relaxation oscillation atthe grid 5 of the said tube 2. The regulating potential is connectedpreferably with any of the stages of the intermediate frequencyamplifier.

I claim:

The operation of the method according to the invention will be describedin a possible embodiment in conjunction with the drawings.

50 The anode of the end tube i of the receiver out- 15 t i m the knownfashlon Wlth 1. In a television receiver for receiving image comm gnd oft B j tube signals, line synchronizing signals and frame Thesynchronisation impulses pass by way o synchronizing signals a voltagegenerating dea filter device 6 to the relaxation oscillation genvice fort ti lly fading compensating, an Erato? W the image Change, which isconamplifier for amplifying the received signals, 55

and a relaxation oscillator for generating the frame deflecting voltagecontrolled by the frame synchronizing signals, said voltage generatingdevice being connected to said amplifier and to said relaxationoscillator in such a fashion that the voltage generated by said deviceis dependent only on the amplitude of the frame synchronizing signals.

2. In a television receiver for receiving image signals, linesynchronizing signals and frame synchronizing signals, a voltagegenerating device for automatically fading compensating, an amplifierfor amplifying the received signals, and a relaxation oscillator forgenerating the frame deflecting voltage controlled by the framesynchronizing signals, said voltage generating device consisting ofcondenser connected in series to a grid controlled tube and shunted by are* sistance, the grid of said tube being coupled to the output of saidrelaxation oscillator in such a fashion that the tube is conductive onlywhen a frame synchronizing impulse arrives.

3. In a television receiver for receiving image signals, linesynchronizing signals and frame synchronizing signals, a voltagegenerating device for automatically fading compensating, an amplifierfor amplifying the received signals, and a relaxation oscillator forgenerating the frame deflecting voltage controlled by the framesynchronizing signals, said voltage generating device consisting of acondenser shunted by a resistance and connected in series to thedischarge of a grid controlled tube, the anode of which being coupled tothe output of said amplifier the cathode of which being connected tosaid condenser and to the grid of said amplifier, the grid of said tubebeing coupled to the output of said relaxation oscillator in such afashion that the tube is conductive only when a frame synchronizingimpulse arrives.

4. In a television receiver for receiving image signals, linesynchronizing signals and frame synchronizing signals, a voltagegenerating device for automatically fading compensating, an amplifierfor amplifying the received signals, and a relaxation oscillator forgenerating the frame deflecting voltage controlled by the framesynchronizing signals, said voltage generating device consisting of acondenser shunted by a resistance and connected in series to thedischarge way of a grid controlled tube, the anode of which beingcoupled by a transformer to the output of said amplifier, the cathode ofwhich being connected to said condenser and to the grid of saidamplifier, the grid of which being biased and coupled to the output ofsaid relaxation oscillator in such a fashion that the tube is conductedonly when a frame synchronizing impulse arrives.

KURT SCI-ILESINGER.

